Oxygen-fuel combuster and method for injecting oxygen and fuel

ABSTRACT

An oxygen-fuel combustor and a method for injecting oxygen and fuel. The oxygen-fuel combustor includes a discharge head unit coupled to a heating furnace and a central supply unit in which, among fuel and primary oxygen, at least the fuel is supplied to the heating furnace. An oxygen supply unit supplies secondary oxygen to the heating furnace. The fuel is injected through a central nozzle unit. Secondary oxygen supplied from the oxygen supply unit is injected through an oxygen nozzle unit. The oxygen nozzle unit includes an accommodation cone part is recessed to decrease in diameter from an entrance. An inclined injection hole part passes through at an incline from the accommodation cone part toward an exit such that the injection direction of the fuel and injection direction of the secondary oxygen cross each other in front of the discharge head unit.

TECHNICAL FIELD

The present invention relates to an oxygen-fuel combustor and a method of injecting oxygen and a fuel, and more particularly, to an oxygen-fuel combustor and a method of injecting oxygen and a fuel, which adopt a unique oxygen injection structure and a unique oxygen injection method to form an invisible wide combustion reaction zone via the high-speed flow of oxygen and the high-speed flow of a fuel and enable the reaction of a high-temperature exhaust gas and a flame by introducing the exhaust gas into the flame.

BACKGROUND ART

In general, an industrial combustor, which is used in steelmaking, casting, and forging processes, forms a flame using a fuel and air as an oxidizer and raises the temperature of a material to be heated by the temperature of the formed flame to improve the convenience of a post-treatment process, and is provided in an industrial furnace. Such a conventional industrial combustor is used in an industrial furnace having a limited space, and is configured such that the fuel is supplied from a fuel nozzle and the room-temperature air is supplied from an air nozzle, which is provided separately from the fuel nozzle to supply the air as an oxidizer, and is preheated to about 500° C. by a recuperator. Due to this configuration, the conventional industrial combustor problematically causes a great amount of pollutants and excessive energy consumption, for example.

On the other hand, a regenerative combustor, in which the air to be used is preheated to a temperature of 1000° C. or higher by waste heat of an exhaust gas, conserves the fuel, similarly to a general oxygen combustor, but has difficulty in maintenance and repair due to the complicated configuration thereof and causes high equipment investment costs and an increased installation area because it is 10 or more times larger than the general oxygen combustor.

In addition, although an oxygen combustor, which forms an adiabatic flame of 800° C. or higher, unlike a flame formed by a general combustor that uses air and a fuel, is used in some special fields, the oxygen combustor may cause a material defect when the material is locally heated by a high-temperature short flame as well as damage to a burner, for example.

In addition, despite 30% or higher energy reduction and 80% or lower exhaust gas emission compared to the general combustor, the oxygen combustor is not used in a general industrial furnace because it tends to generate a large amount of nitrogen oxide (NOx).

In the background art, Korean Patent Laid-Open Publication No. 2003-0061336 (entitled “BURNER FOR DECOMPOSING INCOMBUSTIBLE MATERIAL” and published on Jul. 18, 2003) is disclosed.

DISCLOSURE Technical Problem

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an oxygen-fuel combustor and a method of injecting oxygen and a fuel, which form a wide combustion reaction zone and enable the reaction of a high-temperature exhaust gas and a flame by introducing the exhaust gas into the flame, through the use of a unique oxygen injection structure and a unique oxygen injection method.

Technical Solution

In accordance with one aspect of the present invention, provided is an oxygen-fuel combustor including a discharge head unit coupled to a heating furnace to supply a fuel and oxygen to the heating furnace, the discharge head unit including a discharge body exposed to an inside of the heating furnace to supply the fuel and the oxygen, a center through-portion formed in a center of the discharge body, oxygen through-portions formed in the discharge body so as to be spaced apart from each other in a circumferential direction of an imaginary circle centered on the center through-portion, and a coupling flange provided on an outer peripheral surface of the discharge body for coupling with the heating furnace, a center supply unit coupled to the center through-portion to supply at least the fuel, among the fuel and primary oxygen, to the heating furnace, an oxygen supply unit coupled to the oxygen through-portions to supply secondary oxygen to the heating furnace, a center nozzle unit coupled to the center supply unit or the center through-portion so as to be exposed to the inside of the heating furnace from the center through-portion, the center nozzle unit being configured to inject at least the fuel among the fuel and the primary oxygen supplied from the center supply unit, and an oxygen nozzle unit coupled to the oxygen supply unit or the oxygen through-portions so as to be exposed to the inside of the heating furnace from the oxygen through-portions, the oxygen nozzle unit being configured to inject the secondary oxygen supplied from the oxygen supply unit, and the oxygen nozzle unit includes a conical accommodating portion recessed so as to have a smaller diameter with increasing distance from an inlet of the conical accommodating portion and an inclined injection hole formed obliquely from the conical accommodating portion toward an outlet of the inclined injection a hole so that an injection direction of the fuel and an injection direction of the secondary oxygen cross each other in front of the discharge head unit.

Here, the oxygen nozzle unit further includes an inclination indicator provided at the outlet to of the inclination indicate a direction in which the injection hole is inclined.

Here, an injection angle of the oxygen injected from the inclined injection hole is not less than 2.5 degrees and not more than 30 degrees.

Here, the oxygen through-portions includes first oxygen through-portions formed so as to be spaced apart from each other in a circumferential direction of a first imaginary circle centered on the center through-portion and second oxygen through-portions formed so as to be spaced apart from each other in a circumferential direction of a second imaginary circle that is larger than the first imaginary circle, the oxygen supply unit includes a first oxygen supply unit coupled to the first oxygen through-portions and a second oxygen supply unit coupled to the second oxygen through-portions, and the oxygen nozzle unit includes a first oxygen nozzle unit coupled to the first oxygen supply unit or the first oxygen through-portions so as to be exposed to the inside of the heating furnace from the first oxygen through-portions and a second oxygen nozzle unit coupled to the second oxygen supply unit or the second oxygen through-portions so as to be exposed to the inside of the heating furnace from the second oxygen through-portions.

Here, an injection angle of the secondary oxygen injected from the first oxygen nozzle unit is greater than an injection angle of the secondary oxygen injected from the second oxygen nozzle unit.

Here, an amount of an exhaust gas to be introduced into a flame is adjusted according to at least one of an injection interval of the secondary oxygen, an injection angle of the secondary oxygen, and a collision point of the fuel and the secondary oxygen.

Here, the center supply unit includes a first center supply unit configured to supply one of the fuel and the primary oxygen to the heating furnace and including a first center supply pipe through which the one of the fuel and the primary oxygen to be supplied to the heating furnace is delivered and a second center supply unit coupled to the center through-portion to supply a remaining one of the fuel and the primary oxygen to the heating furnace and including a second center supply pipe through which the remaining one of the fuel and the primary oxygen to be supplied to the heating furnace is delivered in a state in which the first center supply pipe is inserted into the second center supply pipe, and the center nozzle unit includes a center nozzle coupled to the first center supply pipe and having a first injection hole formed therein, from which a fluid delivered from the first center supply pipe is injected, and a nozzle flange protruding from an outer peripheral surface of the center nozzle and coupled to the second center supply pipe, the nozzle flange having a second injection hole formed therein, from which a fluid delivered from the second center supply pipe is injected.

Here, the second injection hole is obliquely formed in the nozzle flange so that an injection direction of the fluid delivered from the second center supply pipe and an injection direction of the fluid delivered from the first center supply pipe cross each other.

Here, the center supply unit includes a first center supply unit configured to supply a primary fuel to the heating furnace and including a first center supply pipe through which the primary fuel to be supplied to the heating furnace is delivered and a second center supply unit coupled to the center through-portion to supply a secondary fuel to the heating furnace and including a second center supply pipe through which the secondary fuel to be supplied to the heating furnace is delivered in a state in which the first center supply pipe is inserted into the second center supply pipe, and the center nozzle unit includes a center nozzle coupled to the first center supply pipe and having a first injection hole formed therein, from which the primary fuel delivered from the first center supply pipe is injected and a nozzle flange protruding from an outer peripheral surface of the center nozzle and coupled to the second center supply pipe, the nozzle flange having a second injection hole formed therein, from which the secondary fuel delivered from the second center supply pipe is injected.

Here, the second injection hole is obliquely formed in the nozzle flange so that an injection direction of the secondary fuel delivered from the second center supply pipe and an injection direction of the oxygen supplied from the oxygen supply unit cross each other.

Here, the second injection hole is provided to correspond to the oxygen nozzle units in a one-to-one ratio.

Here, the oxygen through-portions include two to four oxygen through-portions spaced apart from each other in the circumferential direction.

In accordance with another aspect of the present invention, provided is a method of injecting oxygen and a fuel, the method including measuring an internal temperature of a heating furnace, comparing the internal temperature of the heating furnace measured in the measuring with a predetermined auto-ignition temperature, forming a first flame by injecting primary oxygen and secondary oxygen to the fuel when a result of the comparing is that the internal temperature of the heating furnace is less than the predetermined auto-ignition temperature, and forming a second flame by injecting only the secondary oxygen to the fuel when the result of the comparing is that the internal temperature of the heating furnace is equal to or greater than the predetermined auto-ignition temperature, and, in the forming the first flame, an injection amount of the primary oxygen is 30% or less of a total injection amount of oxygen, and an injection amount of the secondary oxygen is 70% or more of the total injection amount of oxygen.

Here, the forming the first flame includes injecting the fuel forward of a discharge head unit via a center nozzle unit provided at a center of the discharge head unit, injecting the primary oxygen forward of the discharge head unit via the center nozzle unit so as to form a fuel thickening region in which the primary oxygen and the fuel are injected in directions crossing each other and react with each other in front of the discharge head unit, and injecting the secondary oxygen forward of the discharge head unit via an oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from the center nozzle unit, so as to form an oxygen reaction region in which the secondary oxygen and the fuel are injected in directions crossing each other and react with each other in front of the discharge head unit, the oxygen reaction region being formed at a location farther from the discharge head unit than the fuel thickening region.

Here, the injecting the secondary oxygen includes at least one of injecting the secondary oxygen forward of the discharge head unit via a first oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from the center nozzle unit, so as to form a first oxygen reaction region in which the secondary oxygen and the fuel are injected in directions crossing each other and react with each other in front of the discharge head unit, the first oxygen reaction region being formed at a location farther from the discharge head unit than the fuel thickening region and injecting the secondary oxygen forward of the discharge head unit via a second oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from the center nozzle unit, so as to form a second oxygen reaction region in which the secondary oxygen and the fuel are injected in directions crossing each other and react with each other in front of the discharge head unit, the second oxygen reaction region being formed at a location farther from the discharge head unit than the fuel thickening region, the first oxygen reaction region is formed in front of the discharge head unit at a location closer to the discharge head unit than the second oxygen reaction region, and the first oxygen nozzle unit is closer to the center nozzle unit than the second oxygen nozzle unit.

Here, the forming the second flame includes the injecting the fuel and the injecting the secondary oxygen, without the injecting the primary oxygen, compared to the forming the first flame.

In accordance with yet another aspect of the present invention, provided is a method of injecting oxygen and a fuel, the method including measuring an internal temperature of a heating furnace, comparing the internal temperature of the heating furnace measured in the measuring with a predetermined auto-ignition temperature, forming a first flame by injecting at least one of a primary fuel and a secondary fuel to the oxygen when a result of the comparing is that the internal temperature of the heating furnace is less than the predetermined auto-ignition temperature, and forming a second flame by injecting at least one of the primary fuel and the secondary fuel to the oxygen when the result of the comparing is that the internal temperature of the heating furnace is equal to or greater than the predetermined auto-ignition temperature, and, in at least one of the forming the first flame and the forming the second flame, at least one of an oxygen reaction region in which the primary fuel and the oxygen are injected in directions crossing each other and react with each other in front of a discharge head unit and two or more additional reaction regions in which the secondary fuel and the oxygen are injected in directions crossing each other and react with each other between the discharge head unit and the oxygen reaction region is formed.

Here, the forming the first flame includes injecting the oxygen forward of the discharge head unit via an oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from a center nozzle unit provided at a center of the discharge head unit, so as to form at least one of the oxygen reaction region in which the primary fuel and the oxygen are injected in directions crossing each other and react with each other in front of the discharge head unit and the additional reaction regions in which the secondary fuel and the oxygen are injected in directions crossing each other and react with each other, and further includes at least one of injecting the primary fuel to the oxygen reaction region via the center nozzle unit, and injecting the secondary fuel to the additional reaction regions via the center nozzle unit.

Here, the injecting the oxygen includes injecting the oxygen forward of the discharge head unit via a first oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from the center nozzle unit, so as to form a first oxygen reaction region in which the primary fuel and the oxygen are injected in directions crossing each other and react with each other in front of the discharge head unit, and injecting the oxygen forward of the discharge head unit via a second oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from the center nozzle unit, so as to form a second oxygen reaction region in which the primary fuel and the oxygen are injected in directions crossing each other and react with each other in front of the discharge head unit, the first oxygen reaction region is formed in front of the discharge head unit at a location closer to the discharge head unit than the second oxygen reaction region, and the first oxygen nozzle unit is closer to the center nozzle unit than the second oxygen nozzle unit.

The forming the second flame includes injecting the primary fuel to the oxygen reaction region or injecting the secondary fuel to the additional reaction regions via the center nozzle unit, and injecting the oxygen to at least one of the oxygen reaction region or the additional reaction regions according to a type of the fuel injected in the injecting the primary fuel or the secondary fuel.

Here, when the fuel and the oxygen are injected in at least one of the forming the first flame and the forming the second flame, an injection speed of the fuel injected forward of the discharge head unit from the center nozzle unit is equal to or less than 50% of an injection speed of the oxygen injected from the oxygen nozzle unit.

Here, when the fuel and the oxygen are injected in at least one of the forming the first flame and the forming the second flame, an injection speed of the oxygen injected from the oxygen nozzle unit ranges from 100 m/s to 400 m/s.

Advantageous Effects

According to an oxygen-fuel combustor and a method of injecting oxygen and a fuel according to the present invention, through the use of a unique oxygen injection structure and a unique oxygen injection method, it is possible to form a wide combustion reaction zone and to enable the reaction of a high-temperature exhaust gas and a flame by introducing the exhaust gas into the flame. In addition, it is possible to remarkably reduce the amount of nitrogen oxide and realize substantially uniform heating of a material inside a heating furnace owing to a reduction in the adiabatic flame temperature. In addition, it is possible to minimize the size of a heating furnace used in a steelmaking process and to reduce the size of the oxygen-fuel combustor.

In addition, according to the present invention, it is possible to facilitate the collision of a fuel and oxygen, to maximize the effect of flameless combustion due to an impact flame, and to stabilize a combustion reaction. In addition, when the internal temperature of a heating furnace reaches an auto-ignition temperature or higher, it is possible to enhance the collision of a fuel and oxygen and to easily realize a flameless combustion reaction owing to the high-speed flow of the oxygen and the high-speed flow of the fuel.

In addition, according to the present invention, it is possible to stabilize the coupling of oxygen nozzle units, to allow a fuel injected from a center nozzle unit and oxygen injected from the oxygen nozzle units to stably collide with each other in front of a discharge head unit, and to stably induce generation of a flame. In addition, by causing the collision point of the oxygen and the fuel to be forwardly spaced apart from the discharge head unit, it is possible to protect the discharge head unit, the center nozzle unit, and the oxygen nozzle unit from a high-temperature flame of the oxygen and to realize high durability thereof. Moreover, it is possible to achieve a high fuel reduction due to the use of oxygen. In addition, it is possible to selectively form a planar flame or a general flame and to adjust the length of the flame by controlling the structure of the center nozzle unit and the number and arrangement of oxygen nozzle units. In addition, it is possible to allow a high-temperature exhaust gas to be stably introduced into a flame in a non-forcible manner without a separate device and to adjust the amount of the high-temperature exhaust gas to be introduced into the flame.

In addition, according to the present invention, it is possible to induce multistage combustion of oxygen, to facilitate ignition and maintenance of a flame, and to reduce the emission of nitrogen oxide. In addition, it is possible to maximize entrainment for the introduction of a high-temperature exhaust gas via the correlation between the injection speeds of a fuel and oxygen and to maximize recirculation of the exhaust gas in a flame.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an oxygen-fuel combustor according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating the coupled state of the oxygen-fuel combustor according to the first embodiment of the present invention.

FIG. 3 is a view illustrating the arrangement of a center nozzle unit and oxygen nozzle units in the oxygen-fuel combustor according to the first embodiment of the present invention.

FIG. 4 is a view illustrating the modified arrangement of the center nozzle unit and the oxygen nozzle unit in the oxygen-fuel combustor according to the first embodiment of the present invention.

FIG. 5 is a view illustrating the center nozzle unit in the oxygen-fuel combustor according to the first embodiment of the present invention.

FIG. 6 is a view illustrating the oxygen nozzle unit in the oxygen-fuel combustor according to the first embodiment of the present invention.

FIG. 7 is a view illustrating a method of injecting oxygen and a fuel according to the first embodiment of the present invention.

FIG. 8 is a view illustrating the reaction state of oxygen and a fuel according to the first embodiment of the present invention.

FIG. 9 is a perspective view illustrating an oxygen-fuel combustor according to a second embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating the coupled state of the oxygen-fuel combustor according to the second embodiment of the present invention.

FIG. 11 is a view illustrating the arrangement of a center nozzle unit and oxygen nozzle units in the oxygen-fuel combustor according to the second embodiment of the present invention.

FIG. 12 is a view illustrating a modification of the arrangement of the center nozzle unit and the oxygen nozzle units in the oxygen-fuel combustor according to the second embodiment of the present invention.

FIG. 13 is a view illustrating a method of injecting oxygen and a fuel according to the second embodiment of the present invention.

FIG. 14 is a view illustrating the reaction state of oxygen and a fuel according to the second embodiment of the present invention.

FIG. 15 is a perspective view illustrating an oxygen-fuel combustor according to a third embodiment of the present invention.

FIG. 16 is a cross-sectional view illustrating the coupled state of the oxygen-fuel combustor according to the third embodiment of the present invention.

FIG. 17 is a view illustrating the arrangement of a center nozzle unit and oxygen nozzle units in the oxygen-fuel combustor according to the third embodiment of the present invention.

FIG. 18 is a view illustrating the center nozzle unit in the oxygen-fuel combustor according to the third embodiment of the present invention.

FIG. 19 is a view illustrating a method of injecting oxygen and a fuel according to the third embodiment of the present invention.

FIG. 20 is a view illustrating the reaction state of oxygen and a fuel according to the third embodiment of the present invention.

MODE FOR INVENTION

Hereinafter, embodiments of an oxygen-fuel combustor and a method of injecting oxygen and a fuel according to the present invention will be described with reference to the accompanying drawings. Here, the present invention is not restricted or limited by the embodiments. In addition, in the description of the present invention, a detailed description related to well-known functions or configurations may be omitted to clarify the gist of the present invention.

FIG. 1 is a perspective view illustrating an oxygen-fuel combustor according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view illustrating the coupled state of the oxygen-fuel combustor according to the first embodiment of the present invention, FIG. 3 is a view illustrating the arrangement of a center nozzle unit and oxygen nozzle units in the oxygen-fuel combustor according to the first embodiment of the present invention, FIG. 4 is a view illustrating the modified arrangement of the center nozzle unit and the oxygen nozzle unit in the oxygen-fuel combustor according to the first embodiment of the present invention, FIG. 5 is a view illustrating the center nozzle unit in the oxygen-fuel combustor according to the first embodiment of the present invention, FIG. 6 is a view illustrating the oxygen nozzle unit in the oxygen-fuel combustor according to the first embodiment of the present invention, FIG. 7 is a view illustrating a method of injecting oxygen and a fuel according to the first embodiment of the present invention, and FIG. 8 is a view illustrating the reaction state of oxygen and a fuel according to the first embodiment of the present invention.

Now, an oxygen-fuel combustor according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 8. The oxygen-fuel combustor according to the first embodiment of the present invention serves to supply oxygen and a fuel to a heating furnace, and includes a discharge head unit 10, a center supply unit 20, an oxygen supply unit 30, a center nozzle unit 40, and an oxygen nozzle unit 50.

The discharge head unit 10 is coupled to the heating furnace to supply a fuel and oxygen to the heating furnace. The discharge head unit 10 may include a discharge body 11, which is exposed to the inside of the heating furnace to supply the fuel and the oxygen, a center through-portion 13 formed in the center of the discharge body 11, oxygen through-portions 14 formed in the discharge body and spaced apart from each other in the circumferential direction of an imaginary circle C centered on the center through-portion 13, and a coupling flange 12 provided on the outer peripheral surface of the discharge body 11 and coupled to the heating furnace.

As such, when the coupling flange 12 is fixedly coupled to the heating furnace using a separate fastening member in the state in which the discharge body 11 is inserted into a coupling portion of the heating furnace, the entire discharge body 11 may be exposed to the inside of the heating furnace.

Here, two to four oxygen through-portions 14 may be spaced apart from each other in the circumferential direction. This makes it possible to maximize the introduction of a high-temperature exhaust gas into a flame and to reduce the emission of nitrogen oxide (NOx). Here, when the number of oxygen through-portions 14 is one or is more than five, the amount of the high-temperature exhaust gas to be introduced into the flame is reduced, which results in the formation of a general flame.

In addition, the center through-portion 13 is oriented in the same direction as the injection direction of the fuel, and the oxygen through-portions 14 are formed parallel to the center through-portion 13. This may reduce the installation area of the center supply unit 20 and the oxygen supply unit 30 and to ensure efficient supply of the fuel and the oxygen.

The center supply unit 20 supplies at least the fuel, among the fuel and primary oxygen, to the heating furnace. The center supply unit 20 is coupled to the center through-portion 13. The center supply unit 20 includes a first center supply unit 210, which supplies one of the fuel and the primary oxygen to the heating furnace, and a second center supply unit 220, which is coupled to the center through-portion 13 and supplies the other one of the fuel and the primary oxygen to the heating furnace. In one example, when the first center supply unit 210 supplies the fuel, the second center supply unit 220 supplies the primary oxygen. In another example, when the first center supply unit 210 supplies the primary oxygen, the second center supply unit 220 supplies the fuel.

The first center supply unit 210 includes a first center supply pipe 213, through which one of the fuel and the primary oxygen to be supplied to the heating furnace is delivered. The first center supply pipe 213 may be connected to a first center supply chamber 212 in which one of the fuel and the primary oxygen is accommodated. The first center supply chamber 212 may be provided with a first center supply port 211, into which one of the fuel and the primary oxygen is supplied. As such, one of the fuel and the primary oxygen from an external storage container (not illustrated) is accommodated in the first center supply chamber 212 through the first center supply port 211, and is injected from the center nozzle unit 40 after passing through the first center supply pipe 213.

The second center supply unit 220 includes a second center supply pipe 223, which is coupled to the center through-portion 13 and through which the other one of the fuel and the primary oxygen to be supplied to the heating furnace is delivered. The second center supply pipe 223 may be inserted into the center through-portion 13. The second center supply pipe 223 may be connected to a second center supply chamber 222 in which the other one of the fuel and the primary oxygen is accommodated. The second center supply chamber 222 may be provided with a second center supply port 221, into which the other one of the fuel and the primary oxygen is supplied. As such, the other one of the fuel and the primary oxygen from an external storage container (not illustrated) is accommodated in the second center supply chamber 222 through the second center supply port 221, and is injected from the center nozzle unit 40 after passing through the second center supply pipe 223.

Here, the first center supply pipe 213 is inserted into and supported by the second center supply pipe 223 and the second center supply chamber 222, whereby it is possible to reduce the installation area of the center nozzle unit 40 and to ensure efficient supply of the fuel and the primary oxygen.

The oxygen supply unit 30 is coupled to the oxygen through-portions 14 to supply secondary oxygen to the heating furnace. The oxygen supply unit 30 may include oxygen supply pipes 303, which are coupled to the respective oxygen through-portions 14 and through which the secondary oxygen to be supplied to the heating furnace is delivered. The oxygen supply pipe 303 may be inserted into the oxygen through-portion 14. Two to four oxygen supply pipes 303 are provided in the same number as the oxygen through-portions 14. The oxygen supply pipes 303 may be connected to an oxygen supply chamber 302 in which the secondary oxygen is accommodated. In other words, the oxygen supply pipes 303 may be branched from the oxygen supply chamber 302 so as to correspond to the respective oxygen through-portions 14. The oxygen supply chamber 302 may be provided with an oxygen supply port 301, into which the secondary oxygen is supplied. As such, the secondary oxygen from an external storage container (not illustrated) is accommodated in the oxygen supply chamber 302 through the oxygen supply port 301, and is injected from the oxygen nozzle unit 50 after passing through the oxygen supply pipe 303. Here, the second center supply pipe 223 is inserted into the oxygen supply chamber 302, whereby it is possible to reduce the installation area of the oxygen supply unit 30 and to ensure efficient supply of the secondary oxygen.

Although not illustrated, the second center supply chamber 222 may be mounted in or penetrate the oxygen supply chamber 302. In addition, the first center supply chamber 212 may be mounted in or penetrate the second center supply chamber 222.

The center nozzle unit 40 is coupled to the center supply unit 20 so as to be exposed to the inside of the heating furnace from the center through-portion 13. The center nozzle unit 40 may be coupled to the first center supply pipe 213 and to the second center supply pipe 223 so as to be exposed to the inside of the heating furnace from the center through-portion 13. The center nozzle unit 40 may be fitted into the center through-portion 13. At this time, the inside of the center through-portion 13 may be partitioned to correspond to the connection structure of the first center supply pipe 213 and the second center supply pipe 223. In addition, the center nozzle unit 40 injects at least the fuel among the fuel and the primary oxygen supplied from the center supply unit 20. In the first embodiment of the present invention, the center nozzle unit 40 may inject each of the fuel and the primary oxygen supplied from the center supply unit 20.

The center nozzle unit 40 may include a center nozzle 41 coupled to the first center supply pipe 213 and a nozzle flange 42 protruding from the outer peripheral surface of the center nozzle 41 and coupled to the second center supply pipe 223.

The center nozzle 41 may have a first injection hole 411 formed therein so that a fluid delivered from the first center supply pipe 213 is injected through the first injection hole 411. The first injection hole 411 may be formed in the center of the center nozzle. The direction in which the first injection hole 411 is formed may substantially coincide with the direction in which the fluid delivered from the first center supply pipe 213 moves, and may substantially coincide with the injection direction of the fuel. A center conical portion 411 a may be provided at the inlet side of the first injection hole 411 and may be recessed to have a smaller diameter with increasing distance from the inlet. As such, an oxygen reaction region R2 in which the fuel and the secondary oxygen react with each other may be formed at the collision point of the fuel and the secondary oxygen. In addition, the center nozzle 41 may be provided at the edge thereof with a first coupling portion 412 for coupling with the first center supply pipe 213.

The nozzle flange 42 may have a second injection hole 421 formed therein so that a fluid delivered from the second center supply pipe 223 is injected through the second injection hole 421. Two or more second injection holes 421 may be spaced apart from each other along the edge of the nozzle flange 42. Here, the second injection holes 421 may be obliquely formed in the nozzle flange 42 so that the injection direction of the fluid delivered from the second center supply pipe 223 and the injection direction of the fluid delivered from the first center supply pipe 213 cross each other. In other words, the direction in which the second injection hole 421 is formed and the direction in which the first injection hole 411 is formed may cross each other. The two or more second injection holes 421 may be arranged along the periphery of the first injection hole 411 to surround the first injection hole 411. As such, a fuel thickening region R1 in which the primary oxygen and the fuel react with each other may be formed at the collision point of the fuel and the primary oxygen. In addition, the nozzle flange 42 may be provided at the edge thereof with a second coupling portion 422 for coupling with the second center supply pipe 223.

In one example, when the fuel is supplied from the first injection hole 411, the primary oxygen is supplied from the second injection holes. In another example, when the primary oxygen is supplied from the first injection hole 411, the fuel is supplied from the second injection holes 421. This injection of the primary oxygen and the fuel forms a double back-diffusion flame, and causes higher radiant heat transfer than the case where the fuel is supplied from the first injection hole 411.

The oxygen nozzle unit 50 is coupled to the oxygen supply unit 30 so as to be exposed to the inside of the heating furnace from each oxygen through-portion 14. The oxygen nozzle unit 50 may be coupled to each oxygen supply pipe 303 so as to be exposed to the inside of the heating furnace from the oxygen through-portion 14. Two to four oxygen nozzle units 50 may be provided in the same number as the oxygen through-portions 14 or in the same number as the oxygen supply pipes 303. The oxygen nozzle unit 50 may be fitted into the oxygen through-portion 14.

In addition, the oxygen nozzle units 50 inject the oxygen supplied from the oxygen supply unit 30. Two or more oxygen nozzle units 50 may be provided in the same number as the oxygen through-portions 14.

Here, the oxygen nozzle unit 50 may include a conical accommodating portion 502, which is recessed so as to have a smaller diameter with increasing distance from the inlet, and an inclined injection hole 503, which is obliquely formed from the conical accommodating portion 502 toward the outlet so that the injection direction of the fuel and the injection direction of the secondary oxygen cross each other in front of the discharge head unit 10. In other words, the direction in which the inclined injection hole 503 is formed and the direction in which the first injection hole 411 is formed may cross each other. As such, the oxygen reaction region R2 in which the secondary oxygen and the fuel react with each other may be formed at the collision point of the fuel and the secondary oxygen.

The inlet of the oxygen nozzle unit 50 may be defined as a portion of the oxygen nozzle unit 50 into which the oxygen is introduced, and the outlet of the oxygen nozzle unit 50 may be defined as a portion of the oxygen nozzle unit 50 from which the oxygen introduced into the oxygen nozzle unit 50 is discharged.

Particularly, the injection angle A of the oxygen injected from the inclined injection hole 503, which may be referred to as the inclination angle of the inclined injection hole 503 or the injection angle of the secondary oxygen, indicates the angle by which the injection hole 503 is inclined in the oxygen nozzle unit 50 with respect to the injection direction of the fuel so that the injection direction of the fuel and the injection direction of the secondary oxygen cross each other. The injection angle A of the oxygen injected from the inclined injection hole 503 may not be less than 2.5 degrees and not more than 30 degrees.

In addition, the oxygen nozzle unit 50 may include an inclination indicator 504 provided at the outlet to indicate the direction in which the injection hole 503 is inclined. When the oxygen nozzle unit 50 is coupled to the oxygen supply unit 30 or the oxygen through-portion 14, the inclination indicator 504 may assist in the correct positioning of the oxygen nozzle unit 50 in the oxygen through-portion 14 so that the injection direction of the secondary oxygen and the injection direction of the fuel cross each other.

When the oxygen nozzle unit 50 is correctly positioned in the oxygen through-portion 14 via the inclination indicator 504, the inclination indicator 504, the center of the inclined injection hole 503, and the center of the first injection hole 411 in the center nozzle unit 40 are linearly aligned with each other, so that the oxygen injected from the oxygen nozzle unit 50 may collide with the fuel injected from the first injection hole 411 or the second injection hole 421.

In addition, the oxygen nozzle unit 50 may be provided at the edge thereof with a nozzle coupling portion 501 for coupling with the oxygen supply pipe 303.

The amount of an exhaust gas to be introduced into a flame in the oxygen-fuel combustor according to the first embodiment of the present invention may be adjusted according to at least one of the injection interval of the secondary oxygen, the injection angle A of the secondary oxygen, and the collision point of the fuel and the secondary oxygen.

First, as the injection interval of the secondary oxygen increases, the amount of the exhaust gas to be introduced into the flame increases. In addition, as the injection interval of the secondary oxygen decreases, the amount of the exhaust gas to be introduced into the flame may decrease.

Second, as the injection angle A of the secondary oxygen decreases, the amount of the exhaust gas to be introduced into the flame increases. In addition, as the injection angle A of the secondary oxygen increases, the amount of the exhaust gas to be introduced into the flame may decrease. At this time, the injection angle A of the secondary oxygen may be limited to the range of not less than 2.5 degrees and not more than 30 degrees. By limiting the injection angle A of the secondary oxygen to an allowable range as described above, it is possible to maximize the amount of the exhaust gas to be introduced into the flame. When it is attempted to reduce the injection angle A of the secondary oxygen below the allowable range in order to increase the amount of the exhaust gas to be introduced into the flame, no impact flame is formed by collision between the fuel and the secondary oxygen, which may result in a reduction in moderate and intense low oxygen dilution (MILD) combustion. In addition, when the injection angle A of the secondary oxygen is less than the allowable range, the collision and reaction between the fuel and the secondary oxygen become difficult, so that a combustion reaction may not occur or the possibility of incomplete combustion may increase and the generation of carbon monoxide (CO) may increase. On the other hand, when the injection angle A of the secondary oxygen is greater than the allowable range, the position of an impact flame may be excessively close to the discharge head unit 10, which may cause the discharge head unit 10, the center nozzle unit 40, and the oxygen nozzle unit 50 to be damaged by the impact flame, or may cause the impact flame to backflow to the center supply unit 20 or the oxygen supply unit 30.

Third, as the collision point of the fuel and the secondary oxygen becomes farther from the discharge head unit 10, the amount of the exhaust gas to be introduced into the flame may increase. On the other hand, when the collision point of the fuel and the secondary oxygen becomes closer to the discharge head unit 10, the amount of the exhaust gas to be introduced into the flame may decrease. When the collision point deviates from a predetermined allowable range, a desired flame may not be applied to a material inside the heating furnace. In other words, when the collision point of the fuel and the secondary oxygen deviates from the predetermined allowable range, it is possible to form an impact flame between the material inside the heating furnace and the discharge head unit 10. In addition, when the collision point of the fuel and the secondary oxygen deviates from the predetermined allowable range, the impact flame may be excessively close to the discharge head unit 10, which may cause the discharge head unit 10, the center nozzle unit 40, and the oxygen nozzle unit 50 to be damaged by the impact flame, or may cause the impact flame to backflow to the center supply unit 20 or the oxygen supply unit 30.

Although not illustrated, the oxygen-fuel combustor according to the first embodiment of the present invention may further include a control unit. The control unit controls the injection amount of the fuel and the injection amount of the oxygen according to the internal temperature T of the heating furnace. The operation of the control unit will be described below as a method of injecting the oxygen and the fuel according to the first embodiment of the present invention.

Hereinafter, the method of injecting the oxygen and the fuel according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 8. The method of injecting the oxygen and the fuel according to the first embodiment of the present invention is a method of injecting the oxygen and the fuel into the heating furnace, and as illustrated in FIG. 7, includes a temperature measurement step S1, a temperature comparison step S2, a first flame formation step S3, and a second flame formation step S4. The method of injecting the oxygen and the fuel according to the first embodiment of the present invention will be described below as a method of injecting the oxygen and the fuel into the heating furnace via the oxygen-fuel combustor according to the first embodiment of the present invention.

In the temperature measurement step S1, the internal temperature T of the heating furnace is measured. In the temperature measurement step S1, the internal temperature T of the heating furnace may be measured using any of various temperature measurement devices.

In the temperature comparison step S2, the internal temperature T of the heating furnace measured in the temperature measurement step S1 is compared with a predetermined auto-ignition temperature T0. In the temperature comparison step S2, the internal temperature T of the heating furnace may be compared with the predetermined auto-ignition temperature T0 using any of various control units.

In the first flame formation step S3, when the comparison result of the temperature comparison step S2 indicates that the internal temperature T of the heating furnace is less than the predetermined auto-ignition temperature T0, the primary oxygen and the secondary oxygen are injected to the fuel. Here, the predetermined auto-ignition temperature TO may range from 800° C. to 900° C. when the fuel is a liquefied natural gas. In the first flame formation step S3, the injection amount of the primary oxygen is set to 30% or less of the total injection amount of oxygen, and the injection amount of the secondary oxygen is set to 70% or more of the total injection amount of oxygen. The first flame formation step S3 includes a fuel injection step S11, a thickening injection step S12, and a reactive injection step S13. Here, the order of the first flame formation step S3 is not limited thereto, and the order of the first flame formation step S3 may be modified for the formation of a flame.

In the fuel injection step S11 of the first flame formation step S3, the fuel is injected forward of the discharge head unit 10 via the center nozzle unit 40 provided at the center of the discharge head unit 10. In the thickening injection step S12 of the first flame formation step S3, the primary oxygen is injected forward of the discharge head unit 10 via the center nozzle unit 40. Here, the injection amount of the primary oxygen is set to 30% or less of the total injection amount. Through the implementation of the thickening injection step S12, the primary oxygen, which is injected in the direction crossing the injection direction of the fuel, reacts with the fuel in front of the discharge head unit 10, and the fuel thickening region R1 is formed. In the reactive injection step S13 of the first flame formation step S3, the secondary oxygen is injected forward of the discharge head unit 10 via the oxygen nozzle units 50 which are provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40. Here, the injection amount of the secondary oxygen is set to 70% or more of the total injection amount. Through the implementation of the reactive injection step S13, the secondary oxygen, which is injected in the direction crossing the injection direction of the fuel, reacts with the fuel in front of the discharge head unit 10, and the oxygen reaction region R2 is formed at a location farther from the discharge head unit than the fuel thickening region R1. In other words, the fuel thickening region R1 is formed between the discharge head unit 10 and the oxygen reaction region R2. The fuel thickening region R1 and the oxygen reaction region R2 may be partially superimposed on or be spaced apart from each other.

Thereby, the fuel, which has reacted with the primary oxygen but was not combusted in the fuel thickening region R1, finally reacts with the secondary oxygen, whereby it is possible to facilitate ignition and maintenance of the flame and to reduce the emission of nitrogen oxide.

In the second flame formation step S4, when the result of the temperature comparison step S2 indicates that the internal temperature T of the heating furnace is equal to or greater than the predetermined auto-ignition temperature T0, only the secondary oxygen is injected to the fuel. In the second flame formation step S4, the injection amount of the secondary oxygen is 100% of the total injection amount of oxygen. The second flame formation step S4 includes a fuel injection step S11-1 and a reactive injection step S13-1, without the thickening injection step S12, compared to the first flame formation step S3.

In the fuel injection step S11-1 of the second flame formation step S4, the fuel is injected forward of the discharge head unit 10 via the center nozzle unit 40 provided at the center of the discharge head unit 10. In the reactive injection step S13-1 of the second flame formation step S4, the secondary oxygen is injected forward of the discharge head unit 10 via the oxygen nozzle units 50 which are provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40. Here, the injection amount of the secondary oxygen is set to 100% of the total injection amount. Through the implementation of the reactive injection step S13-1, the secondary oxygen, which is injected in the direction crossing the injection direction of the fuel, reacts with the fuel in front of the discharge head unit 10, and only the oxygen reaction region R2 is formed without the formation of the fuel thickening region R1. In other words, the oxygen reaction region is formed at a location forwardly spaced apart from the discharge head unit 10 by a predetermined distance which corresponds to the injection angle A of the secondary oxygen injected via the oxygen nozzle units 50.

Thereby, since the secondary oxygen and the fuel collide with each other to generate a flame only in the oxygen reaction region R2 in the second flame formation step S4, it is possible to maximize entrainment for the introduction of the exhaust gas and to maximize recirculation of the exhaust gas introduced into the flame. In addition, in the second flame formation step S4, a flameless combustion reaction, which is difficult to observe with the naked eye, occurs.

Through the implementation of at least one of the first flame formation step S3 and the second flame formation step S4, when the secondary oxygen is injected from the oxygen nozzle units 50, the high-temperature exhaust gas generated inside the heating furnace is introduced into the flame between the fuel and the secondary oxygen. Thereby, a recirculation region R3 is formed at a location at which the exhaust gas is introduced into the flame. This phenomenon is the recirculation of the exhaust gas, which may rapidly reduce the emission of nitrogen oxide. Particularly, in the first embodiment of the present invention, it is unnecessary to forcibly circulate the exhaust gas generated in the heating furnace or to introduce the exhaust gas into the flame or mix the exhaust gas with oxygen using a separate circulation device, and the recirculation of the exhaust gas may be obtained with a structural feature of the oxygen-fuel combustor according to the first embodiment of the present invention.

In the reaction of the secondary oxygen and the fuel in at least one of the first flame formation step S3 and the second flame formation step S4, since two oxygen nozzle units 50 are provided in two oxygen through-portions 14 and are spaced apart from each other in the circumferential direction of the imaginary circle C, the fuel and the secondary oxygen collide with each other in the oxygen reaction region R2, which is forwardly spaced apart from the discharge head unit 10 by a predetermined distance. Thereby, the flame formed by collision between the fuel and the secondary oxygen may be a fan-shaped flat planar flame having a small thickness and a large width. Thereby, with the formation of the flat planar flame, it is possible to heat a large area with one oxygen-fuel combustor. In addition, in the reaction of the secondary oxygen and the fuel, since three or four oxygen nozzle units 50 are provided in three or four oxygen through-portions 14 in a one-to-one ratio and are equidistantly spaced apart from each other in the circumferential direction of the imaginary circle C, the fuel and the secondary oxygen collide with each other in the oxygen reaction region R2, which is forwardly spaced apart from the discharge head unit 10 by a predetermined distance. Thereby, the flame formed by collision between the fuel and the secondary oxygen may be a general flame and may be used in the general fields of heating.

In addition, when the fuel and the oxygen are injected in at least one of the first flame formation step S3 and the second flame formation step S4, the injection speed of the fuel injected forward of the discharge head unit 10 from the center nozzle unit 40 may be limited to 50% or less of the injection speed of the secondary oxygen injected from the oxygen nozzle units. Such a difference in the injection speed between the fuel and the secondary oxygen may maximize the amount of the high-temperature exhaust gas to be introduced into the flame. In addition, when the fuel and the oxygen are injected in at least one of the first flame formation step S3 and the second flame formation step S4, the injection speed of the secondary oxygen injected from the oxygen nozzle units 50 may be limited to the range from 100 m/s to 400 m/s. This limitation on the injection speed of the secondary oxygen may maximize the amount of the high-temperature exhaust gas to be introduced into the flame.

When the injection speed of the secondary oxygen is less than the limited range, the introduction amount of the high-temperature exhaust gas may decrease and the generation amount of nitrogen oxide may increase. In addition, when the injection speed of the secondary oxygen is less than the limited range, the injection speed of the fuel may increase and no flame reaction may occur. On the other hand, when the injection speed of the secondary oxygen is greater than the limited range, the injection speed of the fuel may decrease, the introduction amount of the exhaust gas may increase, and no flame reaction may occur.

FIG. 9 is a perspective view illustrating an oxygen-fuel combustor according to a second embodiment of the present invention, FIG. 10 is a cross-sectional view illustrating the coupled state of the oxygen-fuel combustor according to the second embodiment of the present invention, FIG. 11 is a view illustrating the arrangement of a center nozzle unit and oxygen nozzle units in the oxygen-fuel combustor according to the second embodiment of the present invention, FIG. 12 is a view illustrating a modification of the arrangement of the center nozzle unit and the oxygen nozzle units in the oxygen-fuel combustor according to the second embodiment of the present invention, FIG. 13 is a view illustrating a method of injecting oxygen and a fuel according to the second embodiment of the present invention, and FIG. 14 is a view illustrating the reaction state of oxygen and a fuel according to the second embodiment of the present invention.

Hereinafter, an oxygen-fuel combustor according to a second embodiment of the present invention will be described with reference to FIGS. 9 to 14. The oxygen-fuel combustor according to the second embodiment of the present invention serves to supply oxygen and a fuel to the heating furnace, and includes the discharge head unit 10, the center supply unit 20, the oxygen supply unit 30, the center nozzle unit 40, and the oxygen nozzle unit 50. In the oxygen-fuel combustor according to the second embodiment of the present invention, the same reference numerals will be given to the same components as those of the oxygen-fuel combustor according to the first embodiment of the present invention, and a description thereof will be omitted.

The oxygen-fuel combustor according to the second embodiment of the present invention includes the oxygen nozzle unit 50 formed in multiple stages. Thus, each oxygen through-portion 14 may include a first oxygen through-portion 15 and a second oxygen through-portion 16, the oxygen supply unit 30 may include a first oxygen supply unit 310 and a second oxygen supply unit 320, and each oxygen nozzle unit 50 may include a first oxygen nozzle unit 510 and a second oxygen nozzle unit 520.

The first oxygen through-portions 15 are formed so as to be spaced apart from each other in the circumferential direction of a first imaginary circle C1 centered on the center through-portion 13. The second oxygen through-portions 16 are formed so as to be spaced apart from each other in the circumferential direction of a second imaginary circle C2, which is larger than the first imaginary circle C1. Here, two to four first oxygen through-portions 15 may be provided, and two to four second oxygen through-portions 16 may be provided. In the second embodiment of the present invention, the first oxygen through-portions 15 and the second oxygen through-portions 16 may be formed in the same number. At this time, the first oxygen through-portion 15 may be disposed on or deviate from an imaginary line that interconnects the center through-portion 13 and the second oxygen through-portion 16. Although not illustrated, the number of first oxygen through-portions 15 and the number of second oxygen through-portions 16 may differ from each other.

The first oxygen supply unit 310 is coupled to the first oxygen through-portions 15. The first oxygen supply unit 310 may include first oxygen supply pipes 313 which are coupled to the first oxygen through-portions 15 and through which the secondary oxygen to be supplied to the heating furnace is delivered. The first oxygen supply pipes 313 may be inserted into the first oxygen through-portions 15. Two to four first oxygen supply pipes 313 are provided in the same number as the first oxygen through-portions 15. The first oxygen supply pipes 313 may be connected to a first oxygen supply chamber 312 in which the secondary oxygen is accommodated. In other words, the first oxygen supply pipes 313 may be branched from the first oxygen supply chamber 312 so as to correspond to the first oxygen through-portions 15. The first oxygen supply chamber 312 may be provided with a first oxygen supply port 311, into which the secondary oxygen is supplied. As such, the secondary oxygen from an external storage container (not illustrated) is accommodated in the first oxygen supply chamber 312 through the first oxygen supply port 311, and is injected from the first oxygen nozzle unit 510 after passing through the first oxygen supply pipe 313. Here, the second center supply pipe 223 may be inserted into the first oxygen supply chamber 312, whereby it is possible to reduce the installation area of the first oxygen supply unit 310 and to ensure efficient supply of the secondary oxygen.

The second oxygen supply unit 320 is coupled to the second oxygen through-portions 16. The second oxygen supply unit 320 may include second oxygen supply pipes 323 which are coupled to the second oxygen through-portions 16 and through which the secondary oxygen to be supplied to the heating furnace is delivered. The second oxygen supply pipes 323 may be inserted into the second oxygen through-portions 16. Two to four second oxygen supply pipes 323 are provided in the same number as the second oxygen through-portions 16. The second oxygen supply pipe 323 may be connected to a second oxygen supply chamber 322 in which the secondary oxygen is accommodated. In other words, the second oxygen supply pipes 323 may be branched from the second oxygen supply chamber 322 so as to correspond to the second oxygen through-portions 16. The second oxygen supply chamber 322 may be provided with a second oxygen supply port 321, into which the secondary oxygen is supplied. As such, the secondary oxygen from an external storage container (not illustrated) is accommodated in the second oxygen supply chamber 322 through the second oxygen supply port 321, and is injected from the second oxygen nozzle unit 520 after passing through the second oxygen supply pipe 323. Here, the second center supply pipe 223 may be inserted into the second oxygen supply chamber 322, whereby it is possible to reduce the installation area of the second oxygen supply unit 320 and to ensure efficient supply of the secondary oxygen. In addition, the second oxygen supply chamber 322 may be disposed between the second center supply chamber 222 and the first oxygen supply chamber 312.

Although not illustrated, the first oxygen supply chamber 312 may be mounted inside the second oxygen supply chamber 322. In addition, the second center supply chamber 222 may be mounted inside the first oxygen supply chamber 312. In addition, the first center supply chamber 212 may be mounted inside the second center supply chamber 222.

The first oxygen nozzle unit 510 is coupled to the first oxygen supply unit 310 or the first oxygen through-portion 15 so as to be exposed to the inside of the heating furnace from the first oxygen through-portion 15. The first oxygen nozzle unit 510 may include the conical accommodating portion 502 and the inclined injection hole 503 as in the first embodiment of the present invention, and may further include at least one of the nozzle coupling portion 501 and the inclination indicator 504. The second oxygen nozzle unit 520 is coupled to the second oxygen supply unit 320 or the second oxygen through-portion 16 so as to be exposed to the inside of the heating furnace from the second oxygen through-portion 16. The second oxygen nozzle unit 520 may include the conical accommodating portion 502 and the inclined injection hole 503 as in the first embodiment of the present invention, and may further include at least one of the nozzle coupling portion 501 and the inclination indicator 504. When the oxygen nozzle unit 50 is formed in multiple stages, the injection angle of the secondary oxygen injected from the first oxygen nozzle unit 510 may be greater than the injection angle of the secondary oxygen injected from the second oxygen nozzle unit 520, so that the oxygen reaction region R2 may include a first oxygen reaction region R21 and a second oxygen reaction region R22. In the first oxygen reaction region R21, the secondary oxygen, which is injected forward of the discharge head unit 10 from the first oxygen nozzle unit 510 in the direction crossing the injection direction of the fuel, reacts with the fuel. In the second oxygen reaction region R22, the secondary oxygen, which is injected forward of the first oxygen reaction region R21 from the second oxygen nozzle unit 520 in the direction crossing the injection direction of the fuel, reacts with the fuel.

Although not illustrated, the oxygen-fuel combustor according to the second embodiment of the present invention may further include a control unit. The control unit controls the injection amount of the fuel and the injection amount of the oxygen according to the internal temperature T of the heating furnace. The operation of the control unit will be described below as a method of injecting the oxygen and the fuel according to the second embodiment of the present invention.

Hereinafter, the method of injecting the oxygen and the fuel according to the second embodiment of the present invention will be described with reference to FIGS. 9 to 14. The method of injecting the oxygen and the fuel according to the second embodiment of the present invention is a method of injecting the oxygen and the fuel into the heating furnace, and as illustrated in FIG. 13, includes the temperature measurement step S1, the temperature comparison step S2, the first flame formation step S3, and the second flame formation step S4. The method of injecting the oxygen and the fuel according to the second embodiment of the present invention will be described as a method of injecting the oxygen and the fuel into the heating furnace via the oxygen-fuel combustor according to the second embodiment of the present invention.

In the temperature measurement step S1, the internal temperature T of the heating furnace is measured. In the temperature measurement step S1, the internal temperature T of the heating furnace may be measured using any of various temperature measurement devices.

In the temperature comparison step S2, the internal temperature T of the heating furnace measured in the temperature measurement step S1 is compared with the predetermined auto-ignition temperature T0. In the temperature comparison step S2, the internal temperature T of the heating furnace may be compared with the predetermined auto-ignition temperature T0 using any of various types of control units (not illustrated).

In the first flame formation step S3, when the comparison result of the temperature comparison step S2 indicates that the internal temperature T of the heating furnace is less than the predetermined auto-ignition temperature T0, the primary oxygen and the secondary oxygen are injected to the fuel. Here, the predetermined auto-ignition temperature T0 may range from 800° C. to 900° C. when the fuel is a liquefied natural gas (LNG). In the first flame formation step S3, the injection amount of the primary oxygen is set to 30% or less of the total injection amount of oxygen, and the injection amount of the secondary oxygen is set to 70% or more of the total injection amount of oxygen. The first flame formation step S3 includes a fuel injection step S21 and a thickening injection step S22, and further includes at least one of a first reactive injection step S23 and a second reactive injection step S24. Here, the order of the first flame formation step S3 is not limited thereto, and the order of the first flame formation step S3 may be modified for the formation of a flame.

In the fuel injection step S21 of the first flame formation step S3, the fuel is injected forward of the discharge head unit 10 via the center nozzle unit 40 provided at the center of the discharge head unit 10. In the thickening injection step S22 of the first flame formation step S3, the primary oxygen is injected forward of the discharge head unit 10 via the center nozzle unit 40. Here, the injection amount of the primary oxygen is set to 30% or less of the total injection amount. Through the implementation of the thickening injection step S22, the primary oxygen, which is injected in the direction crossing the injection of the fuel, reacts with the fuel in front of the discharge head unit 10, and the fuel thickening region R1 is formed. In the first reactive injection step S23 of the first flame formation step S3, the secondary oxygen is injected forward of the discharge head unit 10 via the first oxygen nozzle unit 510 which is provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40. Through the implementation of the first reactive injection step S23, the secondary oxygen, which is injected in the direction crossing the injection direction of the fuel, reacts with the fuel in front of the discharge head unit 10, and the first oxygen reaction region R21 is formed at a location farther from the discharge head unit than the fuel thickening region R1. In other words, the fuel thickening region R1 is formed between the discharge head unit 10 and the first oxygen reaction region R21. Here, the fuel thickening region R1 and the first oxygen reaction region R21 may be partially superimposed on or be spaced apart from each other. In the second reactive injection step S24 of the first flame formation step S3, the secondary oxygen is injected forward of the discharge head unit 10 via the second oxygen nozzle unit 520 which is provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40. Through the implementation of the second reactive injection step S24, the secondary oxygen, which is injected in the direction crossing the injection direction of the fuel, reacts with the fuel in front of the discharge head unit 10, and the second oxygen reaction region R22 is formed at a location farther from the discharge head unit than the fuel thickening region R1. In other words, the first oxygen reaction region R21 and the fuel thickening region R1 may be formed between the discharge head unit 10 and the second oxygen reaction region R22. Here, the fuel thickening region R1, the first oxygen reaction region R21, and the second oxygen reaction region R22 may be partially superimposed on or be spaced apart from each other.

Thereby, the fuel thickening region R1, the first oxygen reaction region R21, and the second oxygen reaction region R22 may be sequentially formed in front of the discharge head unit 10. In addition, at least one of the first oxygen reaction region R21 and the second oxygen reaction region R22 may be formed according to combustion reaction conditions.

Here, the sum of the injection amount of the secondary oxygen injected in the first reactive injection step S23 of the first flame formation step S3 and the injection amount of the secondary oxygen injected in the second reactive injection step S24 of the first flame formation step S3 is set to 70% or more of the total injection amount. When the secondary oxygen is injected from both the first oxygen nozzle unit 510 and the second oxygen nozzle unit 520, the injection amount of the secondary oxygen injected from the first oxygen nozzle unit 510 or the injection speed of the secondary oxygen may be equal to or less than the injection amount of the secondary oxygen injected from the second oxygen nozzle unit 520 or the injection speed of the secondary oxygen, whereby it is possible to maximize recirculation of the exhaust gas.

Thereby, the fuel, which has reacted with the primary oxygen but was not combusted in the fuel thickening region R1, finally reacts with the secondary oxygen in at least one of the first oxygen reaction region R21 and the second oxygen reaction region R22, whereby it is possible to facilitate ignition and maintenance of the flame and to reduce the emission of nitrogen oxide.

Through the implementation of the first flame formation step S3, when the secondary oxygen is injected from at least one of the first oxygen nozzle unit 510 and the second oxygen nozzle unit 520, the high-temperature exhaust gas generated inside the heating furnace is introduced into the flame between the fuel and the secondary oxygen. Thereby, the recirculation region R3 is formed at a location at which the exhaust gas is introduced into the flame. This phenomenon is the recirculation of the exhaust gas, which may rapidly reduce the emission of nitrogen oxide. Particularly, in the second embodiment of the present invention, it is unnecessary to forcibly circulate the exhaust gas generated in the heating furnace or to introduce the exhaust gas into the flame or mix the exhaust gas with oxygen using a separate circulation device, and the recirculation of the exhaust gas may be obtained with a structural feature of the oxygen-fuel combustor according to the second embodiment of the present invention.

In the second flame formation step S4, only the secondary oxygen is injected to the fuel when the result of the temperature comparison step S2 indicates that the internal temperature T of the heating furnace is equal to or greater than the predetermined auto-ignition temperature T0. Particularly, in the second flame formation step S4, the injection amount of the secondary oxygen is 100% of the total injection amount of oxygen.

The second flame formation step S4 includes a fuel injection step S21-1 and further includes at least one of a first reactive injection step S23-1 and a second reactive injection step S24-1, without the thickening injection step S22, compared to the first flame formation step S3.

In the fuel injection step S21-1 of the second flame formation step S4, the fuel is injected forward of the discharge head unit 10 via the center nozzle unit 40 provided at the center of the discharge head unit 10.

In the first reactive injection step S23-1 of the second flame formation step S4, the secondary oxygen is injected forward of the discharge head unit 10 via the first oxygen nozzle unit 510 which is provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40. Through the implementation of the first reactive injection step S23-1, the secondary oxygen, which is injected in the direction crossing the injection direction of the fuel, reacts with the fuel in front of the discharge head unit 10, and the first oxygen reaction region R21 is formed without the formation of the fuel thickening region R1. In other words, the first oxygen reaction region R21 is formed at a location forwardly spaced apart from the discharge head unit 10 by a predetermined distance corresponding to the injection angle of the secondary oxygen via the first oxygen nozzle units 510.

In the second reactive injection step S24-1 of the second flame formation step S4, the secondary oxygen is injected forward of the discharge head unit 10 via the second oxygen nozzle unit 520 which is provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40. Through the implementation of the second reactive injection step S24-1, the secondary oxygen, which is injected in the direction crossing the injection direction of the fuel, reacts with the fuel in front of the discharge head unit 10, and the second oxygen reaction region R22 is formed without the formation of the fuel thickening region R1. In other words, the second oxygen reaction region R22 is formed at a location forwardly spaced apart from the discharge head unit 10 by a predetermined distance corresponding to the injection angle of the secondary oxygen via the second oxygen nozzle unit 520. Thereby, the first oxygen reaction region R21 may be formed between the discharge head unit 10 and the second oxygen reaction region R22. Here, the fuel thickening region R1, the first oxygen reaction region R21, and the second oxygen reaction region R22 may be partially superimposed on or be spaced apart from each other.

Thereby, the first oxygen reaction region R21 and the second oxygen reaction region R22 may be sequentially formed in front of the discharge head unit 10. In addition, at least one of the first oxygen reaction region R21 and the second oxygen reaction region R22 may be formed according to combustion reaction conditions.

Here, the first oxygen reaction region R21 is formed in front of the discharge head unit 10 at a location closer to the discharge head unit than the second oxygen reaction region R22, and the first oxygen nozzle unit 510 is formed closer to the center nozzle unit 40 than the second oxygen nozzle unit 520.

In addition, the sum of the injection amount of the secondary oxygen injected in the first reactive injection step S23-1 of the second flame formation step S4 and the injection amount of the secondary oxygen injected in the second reactive injection step S24-1 of the second flame formation step S4 is 100% of the total injection amount. When the secondary oxygen is injected from both the first oxygen nozzle unit 510 and the second oxygen nozzle unit 520, the injection amount of the secondary oxygen injected from the second oxygen nozzle unit 520 or the injection speed of the secondary oxygen may be equal to or greater than the injection amount of the secondary oxygen injected from the first oxygen nozzle unit 510 or the injection speed of the secondary oxygen, whereby it is possible to maximize recirculation of the exhaust gas.

Thereby, in the second flame formation step S4, since the secondary oxygen and the fuel collide with each other to generate a flame in only at least one of the first oxygen reaction region R21 and the second oxygen reaction region R22, it is possible to maximize entrainment for the introduction of the exhaust gas and to maximize recirculation of the exhaust gas. In addition, in the second flame formation step S4, a flameless combustion reaction, which is difficult to observe with the naked eye, occurs.

In the reaction of the secondary oxygen and the fuel in the first flame formation step S3 or the second flame formation step S4, in order to heat an area that is relatively close to the discharge head unit 10, the secondary oxygen and the fuel may be injected via the first oxygen nozzle unit 510 and the center nozzle unit 40 to form a relatively short flame. In addition, in order to heat an area that is relatively far from the discharge head unit 10, the secondary oxygen and the fuel may be injected via the second oxygen nozzle unit 520 and the center nozzle unit 40 to form a relatively long flame. In addition, in order to heat the entire area in front of the discharge head unit 10, the secondary oxygen and the fuel may be injected via the first oxygen nozzle unit 510, the second oxygen nozzle unit 520, and the center nozzle unit 40, which may increase the area over which a flame is formed.

In the reaction of the secondary oxygen and the fuel in at least one of the first flame formation step S3 and the second flame formation step S4, since two first oxygen nozzle units 510 are provided in two first oxygen through-portions 15, two second oxygen nozzle units 520 are provided in two second oxygen through-portions 16, and the center nozzle unit 40, the first oxygen nozzle units 510, and the second oxygen nozzle units 520 are arranged on a straight line, the fuel and the secondary oxygen collide with each other in at least one of the first oxygen reaction region R21 and the second oxygen reaction region R22, which are forwardly spaced apart from the discharge head unit 10 by predetermined distances. Thereby, the flame formed by collision between the fuel and the secondary oxygen may be a fan-shaped flat planar flame having a small thickness and a large width. With the formation of the flat planar flame, it is possible to heat a large area with one oxygen-fuel combustor.

In addition, in the reaction of the secondary oxygen and the fuel, when two first oxygen nozzle units 510 are provided in two first oxygen through-portions 15, two second oxygen nozzle units 520 are provided in two second oxygen through-portions 16, and an imaginary line that interconnects the center nozzle unit 40 and the first oxygen nozzle units 510 and an imaginary line that interconnects the center nozzle unit 40 and the second oxygen nozzle units 520 cross each other, the secondary oxygen and the fuel collide with each other in at least one of the first oxygen reaction region R21 and the second oxygen reaction region R22, which are forwardly spaced apart from the discharge head unit 10 by predetermined distances. Thereby, the flame formed by collision between the fuel and the secondary oxygen may be a general flame and may be used in the general fields of heating. In addition, in the reaction of the secondary oxygen and the fuel, when three or four first oxygen nozzle units 510 are provided to correspond to three or four first oxygen through-portions 15 in a one-to-one ratio and are equidistantly spaced apart from each other in the circumferential direction of the first imaginary circle C1 and three or four second oxygen nozzle units 520 are provided to correspond to three or four second oxygen through-portions 16 in a one-to-one ratio and are equidistantly spaced apart from each other in the circumferential direction of the second imaginary circle C2, the fuel and the secondary oxygen collide with each other in at least one of the first oxygen reaction region R21 and the second oxygen reaction region R22, which are forwardly spaced apart from the discharge head unit 10 by predetermined distances. Thereby, the flame formed by collision between the fuel and the secondary oxygen may be a general flame and may be used in the general fields of heating.

In addition, when the fuel and the oxygen are injected in at least one of the first flame formation step S3 and the second flame formation step S4, the injection speed of the fuel injected forward of the discharge head unit 10 from the center nozzle unit 40 may be limited to 50% or less of the injection speed of the secondary oxygen injected from the first oxygen nozzle unit 510 or the second oxygen nozzle unit 520. Such a difference between the injection speed of the fuel and the injection speed of the secondary oxygen may maximize the amount of the exhaust gas to be introduced into the flame. In addition, when the fuel and the oxygen are injected in at least one of the first flame formation step S3 and the second flame formation step S4, the injection speed of the secondary oxygen injected from the first oxygen nozzle unit 510 or the second oxygen nozzle unit 520 may be limited to the range from 100 m/s to 400 m/s. This limitation on the injection speed of the secondary oxygen may maximize the amount of the high-temperature exhaust gas to be introduced into the flame.

When the injection speed of the secondary oxygen is below the limited range, the introduction amount of the high-temperature exhaust gas may decrease and the generation amount of nitrogen oxide may increase. In addition, when the injection speed of the secondary oxygen is below the limited range, the injection speed of the fuel may increase and no flame reaction may occur. On the other hand, when the injection speed of the secondary oxygen is above the limited range, the injection speed of the fuel may decrease, the introduction amount of the exhaust gas may increase, and no flame reaction may occur.

Although not illustrated, the oxygen-fuel combustor according to the second embodiment of the present invention may further include a control unit. The control unit controls the injection amount of the fuel and the injection amount of the oxygen according to the internal temperature T of the heating furnace. The operation of the control unit will be described as a method of injecting the oxygen and the fuel according to the second embodiment of the present invention.

FIG. 15 is a perspective view illustrating an oxygen-fuel combustor according to a third embodiment of the present invention, FIG. 16 is a cross-sectional view illustrating the coupled state of the oxygen-fuel combustor according to the third embodiment of the present invention, FIG. 17 is a view illustrating the arrangement of a center nozzle unit and oxygen nozzle units in the oxygen-fuel combustor according to the third embodiment of the present invention, FIG. 18 is a view illustrating the center nozzle unit in the oxygen-fuel combustor according to the third embodiment of the present invention, FIG. 19 is a view illustrating a method of injecting oxygen and a fuel according to the third embodiment of the present invention, and FIG. 20 is a view illustrating the reaction state of oxygen and a fuel according to the third embodiment of the present invention.

Hereinafter, an oxygen-fuel combustor according to a third embodiment of the present invention will be described with reference to FIGS. 15 to 20. The oxygen-fuel combustor according to the third embodiment of the present invention serves to supply oxygen and a fuel to the heating furnace, and includes the discharge head unit 10, the center supply unit 20, the oxygen supply unit 30, the center nozzle unit 40, and the oxygen nozzle unit 50.

In the oxygen-fuel combustor according to the third embodiment of the present invention, the same reference numerals will be given to the same components as those of the oxygen-fuel combustor according to the first embodiment or the second embodiment of the present invention, and a description thereof will be omitted.

The oxygen-fuel combustor according to the third embodiment of the present invention is formed so as to inject only the fuel from the center nozzle unit 40.

Accordingly, the center supply unit 20 may include the first center supply unit 210, which supplies primary fuel to the heating furnace, and the second center supply unit 220, which supplies secondary fuel to the heating furnace, and the center nozzle unit 40 may include the center nozzle 41 and the nozzle flange 42. The sum of the primary fuel and the secondary fuel is set to 100% of the total injection amount of fuel. The primary fuel and the secondary fuel may be the same fuel.

The first center supply unit 210 includes the first center supply pipe 213 through which the primary fuel to be supplied to the heating furnace is delivered. The first center supply pipe 213 may be connected to the first center supply chamber 212 in which the primary fuel is accommodated. The first center supply chamber 212 may be provided with the first center supply port 211, into which the primary fuel is supplied. As such, the primary fuel from an external storage container (not illustrated) is accommodated in the first center supply chamber 212 through the first center supply port 211, and is injected from the center nozzle unit 40 after passing through the first center supply pipe 213.

The second center supply unit 220 includes the second center supply pipe 223, which is connected to the center through-portion 13 and through which the secondary fuel to be supplied to the heating furnace is delivered. The second center supply pipe 223 may be inserted into the center through-portion 13. The second center supply pipe 222 may be connected to the second center supply chamber 222 in which the secondary fuel is accommodated. The second center supply chamber 222 may be provided with the second center supply port 221, into which the secondary fuel is supplied. As such, the secondary fuel from an external storage container (not illustrated) is accommodated in the second center supply chamber 222 through the second center supply port 221, and is injected from the center nozzle unit 40 after passing through the second center supply pipe 223. Here, the first center supply pipe 213 may be inserted into and supported by the second center supply pipe 223 and the second center supply chamber 222, whereby it is possible to reduce the size of the center nozzle unit 40 and to ensure efficient supply of the primary fuel and the secondary fuel.

The center nozzle unit 40 is coupled to the center supply unit 20 so as to be exposed to the inside of the heating furnace from the center through-portion 13. The center nozzle unit 40 may be coupled to both the first center supply pipe 213 and the second center supply pipe 223 so as to be exposed to the inside of the heating furnace from the center through-portion 13. The center nozzle unit 40 may be fitted into the center through-portion 13. At this time, the inside of the center through-portion 13 may be partitioned to correspond to the connection structure of the first center supply pipe 213 and the second center supply pipe 223.

In addition, the center nozzle unit 40 injects the primary fuel supplied from the first center supply unit 210 and the secondary fuel supplied from the second center supply unit 220. In the third embodiment of the present invention, the center nozzle unit 40 is capable of injecting the primary fuel supplied from the first center supply unit 210 and the secondary fuel supplied from the second center supply unit 220, respectively. The center nozzle unit 40 may include the center nozzle 41 coupled to the first center supply pipe 213 and the nozzle flange 42 protruding from the outer peripheral surface of the center nozzle 41 and coupled to the second center supply pipe 223.

The center nozzle 41 may have the first injection hole 411 formed therein so that the primary fuel delivered from the first center supply pipe 213 is injected from the first injection hole. The first injection hole 411 may be formed in the center of the center nozzle 41. The direction in which the first injection hole 411 is formed may substantially coincide with the direction in which the primary fuel delivered from the first center supply pipe 213 moves, and may substantially coincide with the injection direction of the primary fuel. The center conical portion 411 a may be recessed at the inlet side of the first injection hole 411 so as to have a smaller diameter with increasing distance from the inlet. As such, the oxygen reaction region R2 in which the secondary fuel and the oxygen react with each other may be formed at the collision point of the secondary fuel and the oxygen. In addition, the center nozzle 41 may be provided at the edge thereof with the first coupling portion 412 for coupling with the first center supply pipe 213.

The nozzle flange 42 may have the second injection hole 421 formed therein so that the secondary fuel delivered from the second center supply pipe 223 is injected from the second injection hole. Two or more second injection holes 421 may be spaced apart from each other along the edge of the nozzle flange 42.

Here, the second injection holes 421 may be obliquely formed in the nozzle flange 42 so that the injection direction of the secondary fuel delivered from the second center supply pipe 223 and the injection direction of the oxygen delivered from the oxygen supply pipe 303 of the oxygen supply unit 30 cross each other. Particularly, each second injection hole 421 may be disposed on an imaginary line that interconnects the first injection hole 411 and the inclined injection hole 503 so as to correspond to the oxygen nozzle unit 50. In other words, the direction in which the second injection hole 421 is formed and the direction in which the inclined injection hole 503 is formed may cross each other. More specifically, the second injection holes 421 and the oxygen nozzle units 50 may be formed in the same number. Thereby, an additional reaction region R4 in which the secondary fuel and oxygen react with each other may be formed at the collision point of the secondary fuel and the oxygen. In addition, the nozzle flange 42 may be provided at the edge thereof with the second coupling portion 422 for coupling with the second center supply pipe 223.

Although not illustrated, in the third embodiment of the present invention, each oxygen through-portion 14 may include the first oxygen through-portion 15 and the second oxygen through-portion 16 as in the second embodiment of the present invention, the oxygen supply unit 30 may include the first oxygen supply unit 310 and the second oxygen supply unit 320 as in the second embodiment of the present invention, and each oxygen nozzle unit 50 may include the first oxygen nozzle unit 510 and the second oxygen nozzle unit 520 as in the second embodiment of the present invention.

The oxygen-fuel combustor according to the third embodiment of the present invention may further include a control unit. The control unit controls the injection amount of the fuel and the oxygen according to the internal temperature T of the heating furnace. The operation of the control unit will be described as a method of injecting the oxygen and the fuel according to the third embodiment of the present invention.

Hereinafter, the method of injecting the oxygen and the fuel according to the third embodiment of the present invention will be described with reference to FIGS. 15 to 20. The method of injecting the oxygen and the fuel according to the third embodiment of the present invention is a method of injecting the oxygen and the fuel into a heating furnace, and as illustrated in FIG. 19, includes the temperature measurement step S1, the temperature comparison step S2, the first flame formation step S3, and the second flame formation step S4. The method of injecting the oxygen and the fuel according to the third embodiment of the present invention will be described as a method of injecting the oxygen and the fuel into the furnace via the oxygen-fuel combustor according to the third embodiment of the present invention.

In the third embodiment of the present invention, in at least one of the first flame formation step S3 and the second flame formation step S4, at least one of the oxygen reaction region R2 in which the primary fuel, which is injected in the direction crossing the injection direction of the oxygen, reacts with the oxygen in front of the discharge head unit 10 and two or more additional reaction regions R4 in which the secondary fuel, which is injected in the direction crossing the injection direction of the oxygen, reacts with the oxygen between the discharge head unit 10 and the oxygen reaction region R2 is formed. The two or more additional reaction regions R4 may be superimposed on or spaced apart from each other.

In the temperature measurement step S1, the internal temperature of the heating furnace is measured. In the temperature measurement step S1, the internal temperature T of the heating furnace may be measured using any of various temperature measurement devices (not illustrated).

In the temperature comparison step S2, the internal temperature T of the heating furnace measured in the temperature measurement step S1 is compared with the predetermined auto-ignition temperature T0. In the temperature comparison step S2, the internal temperature T of the heating furnace may be compared with the predetermined auto-ignition temperature T0 using any of various control units (not illustrated).

In the first flame formation step S3, when the comparison result of the temperature comparison step S2 indicates that the internal temperature T of the heating furnace is less than the predetermined auto-ignition temperature T0, at least one of the primary fuel and the secondary fuel is injected to the oxygen. The predetermined auto-ignition temperature T0 may range from 800° C. to 900° C. when the fuel is a liquefied natural gas.

The first flame formation step S3 includes a reactive injection step S33 and further includes at least one of a first fuel injection step S31 and a second fuel injection step S32. Here, the order of the first flame formation step S3 is not limited thereto, and the order of the first flame formation step S3 may be modified for the formation of a flame.

In the reactive injection step S33 of the first flame formation step S3, the oxygen is injected forward of the discharge head unit 10 via the oxygen nozzle unit 50 which is provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40 provided at the center of the discharge head unit 10. Through the implementation of the reactive injection step S33, at least one of the oxygen reaction region R2 in which the primary fuel, which is injected in the direction crossing the injection direction of the oxygen, reacts with the oxygen in front of the discharge head unit 10 and the additional reaction region R4 in which the secondary fuel, which is injected in the direction crossing the injection direction of the oxygen, reacts with the oxygen is formed. Here, the oxygen reaction region R2 and the additional reaction region R4 may be partially superimposed on or be spaced apart from each other. Although not illustrated, in the third embodiment of the present invention, when the oxygen injection nozzles 50 are formed in multiple stages, the reactive injection step S33 may include at least one of a first reactive injection step and a second reactive injection step as in the second embodiment of the present invention.

In the first reactive injection step, the oxygen is injected forward of the discharge head unit 10 via the first oxygen nozzle unit 510 which is provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40, so that the first oxygen reaction region R21 in which the primary fuel and the oxygen, which are injected in the directions crossing each other, react with each other in front of the discharge head unit 10 is formed. In the second reactive injection step, the oxygen is injected forward of the discharge head unit 10 via the second oxygen nozzle unit 520 which is provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40, so that the second oxygen reaction region R22 in which the oxygen and the primary fuel, which are injected in the directions crossing each other, react with each other in front of the discharge head unit 10 is formed.

Here, the first oxygen reaction region R21 is formed at a location closer to the discharge head unit 10 than the second oxygen reaction region R22. In addition, the first oxygen nozzle unit 510 is formed closer to the center nozzle unit 40 than the second oxygen nozzle unit 520. In other words, the second oxygen nozzle unit 520 is formed farther from the center nozzle unit 40 than the first oxygen nozzle unit 510.

In the first fuel injection step S31 of the first flame formation step S3, the primary fuel is injected to the oxygen reaction region R2 via the center nozzle unit 40. The primary fuel is injected forward of the discharge head unit 10 via the center nozzle unit 40 provided at the center of the discharge head unit 10. Through the implementation of the first fuel injection step S31, the oxygen reaction region R2 in which the primary fuel and the oxygen, which are injected in the directions crossing each other, react with each other in front of the discharge head unit 10 is formed.

In the second fuel injection step S32 of the first flame formation step S3, the secondary fuel is injected to the additional reaction region R4 via the center nozzle unit 40. Through the implementation of the secondary fuel injection step S32, the additional reaction region R4 in which the secondary fuel and the oxygen, which are injected in the directions crossing each other, react with each other is formed.

Thereby, the oxygen, which has reacted with the secondary fuel but was not combusted in the additional reaction region R4, finally reacts with the primary fuel in the oxygen reaction region R2, whereby it is possible to facilitate ignition and maintenance of a flame and to reduce the emission of nitrogen oxide.

When the primary fuel and the secondary fuel are injected respectively by 50% from the center nozzle unit 40, all of the primary fuel and the secondary fuel may react with each other to form a wide and long flame. Here, as the injection amount of the primary fuel becomes greater than the injection amount of the secondary fuel, the flame may be formed at a longer distance from the discharge head unit 10. As the injection amount of the primary fuel becomes smaller than the injection amount of the secondary fuel, the flame may be formed at a shorter distance from the discharge head unit 10.

In the second flame formation step S4, when the result of the temperature comparison step S2 indicates that the internal temperature T of the heating furnace is equal to or greater than the predetermined auto-ignition temperature T0, at least one of the primary fuel or the secondary fuel is injected to the oxygen. The second flame formation step S4 includes a fuel adjustment step S31-1 and an oxygen adjustment step S33-1.

In the fuel adjustment step S31-1 of the second flame formation step S4, through the use of the center nozzle unit 40, the primary fuel is injected to the oxygen reaction region R2, or the secondary fuel is injected to the additional reaction region R4. In the oxygen adjustment step S33-1 of the second flame formation step S4, the oxygen is injected to at least one of the oxygen reaction region R2 and the additional reaction region R4 according to the type of the fuel injected in the fuel adjustment step S31-1.

Although not illustrated, in the third embodiment of the present invention, when the oxygen injection nozzles are formed in multiple stages, the oxygen adjustment step S33-1 may include at least one of a first oxygen adjustment step and a second oxygen adjustment step as in the second embodiment of the present invention.

In the first oxygen adjustment step, the oxygen is injected forward of the discharge head unit 10 via the first oxygen nozzle unit 510 which is provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40 so that the first oxygen reaction region R21 in which the primary fuel and the oxygen, which are injected in the directions crossing each other, react with each other in front of the discharge head unit 10 is formed.

In the second oxygen adjustment step, the oxygen is injected forward of the discharge head unit 10 via the second oxygen nozzle unit 520 which is provided in the discharge head unit 10 so as to be spaced apart from the center nozzle unit 40 so that the second oxygen reaction region R22 in which the primary fuel and the oxygen, which are injected in the directions crossing each other, react with each other in front of the discharge head unit 10 is formed.

Here, the first oxygen reaction region R21 is formed in front of the discharge head unit 10 at a location closer to the discharge head unit than the second oxygen reaction region R22. In addition, the first oxygen nozzle unit 510 is formed far the from the center nozzle unit 40 than the second oxygen nozzle unit 520.

Through the implementation of the fuel adjustment step S31-1 and the oxygen adjustment step S33-1, the oxygen reaction region R2 in which the primary fuel and the oxygen are injected in the directions crossing each other and react with each other is formed, and the additional reaction region R4 in which the secondary fuel and the oxygen are injected in the directions crossing each other and react with each other is formed.

Thereby, in the second flame formation step S4, since the oxygen and the fuel collide with each other to generate a flame in at least one of the oxygen reaction region R2 and the additional reaction region R4, it is possible to maximize entrainment for the introduction of the exhaust gas and to maximize recirculation of the exhaust gas to be introduced into the flame. In addition, in the second flame formation step S4, a flameless combustion reaction, which is difficult to observe with the naked eye, occurs.

Through the implementation of at least one of the first flame formation step S3 and the second flame formation step S4, when the oxygen is injected from the oxygen nozzle unit 50, the high-temperature exhaust gas generated inside the heating furnace is introduced into the flame between the primary fuel and the oxygen and between the secondary fuel and the oxygen. Thereby, the recirculation region R3 is formed at a location at which the exhaust gas is introduced into the flame. This phenomenon is the recirculation of the exhaust gas, which may rapidly reduce the emission of nitrogen oxide. Particularly, in the third embodiment of the present invention, it is unnecessary to forcibly circulate the exhaust gas generated in the heating furnace or to introduce the exhaust gas into the flame or mix the exhaust gas with oxygen using a separate circulation device, and the recirculation of the exhaust gas may be obtained with a structural feature of the oxygen-fuel combustor according to the third embodiment of the present invention.

In the reaction of the oxygen and the fuel according to at least one of the first flame formation step S3 and the second flame formation step S4, the number of oxygen nozzle units 50 and the arrangement structure thereof exert the same function and effect as those in the first embodiment or the second embodiment.

In addition, when the fuel and the oxygen are injected in at least one of the first flame formation step S3 and the second flame formation step S4, the injection speed of the fuel injected forward of the discharge head unit 10 from the center nozzle unit 40 may be limited to 50% or less of the injection speed of oxygen injected from the oxygen nozzle unit 50. Such a difference between the injection speed of the fuel and the injection speed of the oxygen may maximize the amount of the high-temperature exhaust gas to be introduced into the flame. In addition, when the fuel and the oxygen are injected in at least one of the first flame formation step S3 and the second flame formation step S4, the injection speed of the oxygen injected from the oxygen nozzle unit 50 may be limited to the range from 100 m/s to 400 m/s. This limitation on the injection speed of the oxygen may maximize the amount of the high-temperature exhaust gas to be introduced into the flame. When the injection speed of the oxygen is less than the limited range, the introduction amount of the high-temperature exhaust gas may decrease and the generation amount of nitrogen oxide may increase. In addition, when the injection speed of the oxygen is less than the limited range, the injection speed of the fuel may increase and no flame reaction may occur. On the other hand, when the injection speed of the oxygen is greater than the limited range, the injection speed of the fuel may decrease, the introduction amount of the exhaust gas may increase, and no flame reaction may occur.

According to the oxygen-fuel combustor and the method of injecting the oxygen and the fuel described above, through the use of a unique oxygen injection structure and a unique oxygen injection method, it is possible to form a wide combustion reaction zone, to enable re-combustion of a high-temperature exhaust gas by introducing the exhaust gas into a flame, and to remarkably reduce the amount of nitrogen oxide and realize substantially uniform heating of a material inside a heating furnace owing to a reduction in the adiabatic flame temperature. In addition, it is possible to minimize the size of a heating furnace used in a steelmaking process and to reduce the size of the oxygen-fuel combustor. In addition, it is possible to facilitate the collision of the fuel and the oxygen, to maximize the effect of flameless combustion due to an impact flame, and to stabilize a combustion reaction. In addition, when the internal temperature of the heating furnace reaches the auto-ignition temperature T0 or higher, it is possible to enhance the collision of the fuel and the oxygen and to easily realize a flameless combustion reaction owing to the high-speed flow of the oxygen and the high-speed flow of the fuel.

In addition, it is possible to stabilize the coupling of the oxygen nozzle units 50, to allow the fuel injected from the center nozzle unit 40 and the oxygen injected from the oxygen nozzle units to stably collide with each other in front of the discharge head unit 10, and to stably induce generation of a flame.

In addition, by causing the collision point of the oxygen and the fuel to be forwardly spaced apart from the discharge head unit 10, it is possible to protect the discharge head unit 10, the center nozzle unit 40, and the oxygen nozzle unit 50 from a high-temperature flame of the oxygen and to realize high durability thereof. Moreover, it is possible to achieve a high fuel reduction due to the use of oxygen. In addition, it is possible to selectively form a planar flame or a general flame and to adjust the length of the flame by controlling the structure of the center nozzle unit 40 and the number and arrangement of oxygen nozzle units 50. In addition, it is possible to allow a high-temperature exhaust gas to be stably introduced into a flame in a non-forcible manner without a separate device and to adjust the amount of the high-temperature exhaust gas to be introduced into the flame. In addition, it is possible to induce multistage combustion of oxygen, to facilitate ignition and maintenance of a flame, and to reduce the emission of nitrogen oxide.

In addition, it is possible to maximize entrainment for the introduction of the high-temperature exhaust gas via the correlation between the injection speeds of the fuel and the oxygen and to maximize recirculation of the exhaust gas in the flame.

While the exemplary embodiments of the present invention have been described above with reference to the drawings, the present invention may be modified or changed in various ways by those skilled in the art without departing from the sprit and range of the present invention described in the following claims.

INDUSTRIAL APPLICABILITY

The present invention may be applied to an oxygen-fuel combustor, which is capable of reducing the consumption of a fuel using oxygen, forming a flat planar flame or a general flame for uniformly heating a material in an industrial furnace used in a steelmaking process, and adjusting the length of the flame, and may characterize a method of injecting oxygen and a fuel. 

1. An oxygen-fuel combustor comprising: a discharge head unit coupled to a heating furnace to supply a fuel and oxygen to the heating furnace, the discharge head unit comprising a discharge body exposed to an inside of the heating furnace to supply the fuel and the oxygen, a center through-portion formed in a center of the discharge body, oxygen through-portions formed in the discharge body so as to be spaced apart from each other in a circumferential direction of an imaginary circle centered on the center through-portion, and a coupling flange provided on an outer peripheral surface of the discharge body for coupling with the heating furnace; a center supply unit coupled to the center through-portion to supply at least the fuel, among the fuel and primary oxygen, to the heating furnace; an oxygen supply unit coupled to the oxygen through-portions to supply secondary oxygen to the heating furnace; a center nozzle unit coupled to the center supply unit or the center through-portion so as to be exposed to the inside of the heating furnace from the center through-portion, the center nozzle unit being configured to inject at least the fuel among the fuel and the primary oxygen supplied from the center supply unit; and an oxygen nozzle unit coupled to the oxygen supply unit or the oxygen through-portions so as to be exposed to an inside of the heating furnace from the oxygen through-portions, the oxygen nozzle unit being configured to inject the secondary oxygen supplied from the oxygen supply unit, wherein the oxygen nozzle unit comprises: a conical accommodating portion recessed so as to have a smaller diameter with increasing distance from an inlet of the conical accommodating portion; and an inclined injection hole formed obliquely from the conical accommodating portion toward an outlet of the inclined injection a hole so that an injection direction of the fuel and an injection direction of the secondary oxygen cross each other in front of the discharge head unit.
 2. The oxygen-fuel combustor according to claim 1, wherein the oxygen nozzle unit further comprises an inclination indicator provided at the outlet of the inclination indicator to indicate a direction in which the injection hole is inclined.
 3. The oxygen-fuel combustor according to claim 1, wherein an injection angle of the oxygen injected from the inclined injection hole is not less than 2.5 degrees and not more than 30 degrees.
 4. The oxygen-fuel combustor according to claim 1, wherein the oxygen through-portions comprise: a first oxygen through-portions formed so as to be spaced apart from each other in a circumferential direction of a first imaginary circle centered on the center through-portion; and second oxygen through-portions formed so as to be spaced apart from each other in a circumferential direction of a second imaginary circle that is larger than the first imaginary circle, wherein the oxygen supply unit comprises: a first oxygen supply unit coupled to the first oxygen through-portions; and a second oxygen supply unit coupled to the second oxygen through-portions, and wherein the oxygen nozzle unit comprises: a first oxygen nozzle unit coupled to the first oxygen supply unit or the first oxygen through-portions so as to be exposed to the inside of the heating furnace from the first oxygen through-portions; and a second oxygen nozzle unit coupled to the second oxygen supply unit or the second oxygen through-portions so as to be exposed to the inside of the heating furnace from the second oxygen through-portions.
 5. The oxygen-fuel combustor according to claim 1, wherein an amount of an exhaust gas to be introduced into a flame is adjusted according to at least any one of an injection interval of the secondary oxygen, an injection angle of the secondary oxygen, and a collision point of the fuel and the secondary oxygen.
 6. The oxygen-fuel combustor according to claim 1, wherein the center supply unit comprises: a first center supply unit configured to supply one of the fuel and the primary oxygen to the heating furnace and comprising a first center supply pipe through which the one of the fuel and the primary oxygen to be supplied to the heating furnace is delivered; and a second center supply unit coupled to the center through-portion to supply a remaining one of the fuel and the primary oxygen to the heating furnace and comprising a second center supply pipe through which the remaining one of the fuel and the primary oxygen to be supplied to the heating furnace is delivered in a state in which the first center supply pipe is inserted into the second center supply pipe, and wherein the center nozzle unit comprises a center nozzle coupled to the first center supply pipe and having a first injection hole formed therein, from which a fluid delivered from the first center supply pipe is injected; and a nozzle flange protruding from an outer peripheral surface of the center nozzle and coupled to the second center supply pipe, the nozzle flange having a second injection hole formed therein, from which a fluid delivered from the second center supply pipe is injected.
 7. The oxygen-fuel combustor according to claim 6, wherein the second injection hole is obliquely formed in the nozzle flange so that an injection direction of the fluid delivered from the second center supply pipe and an injection direction of the fluid delivered from the first center supply pipe cross each other.
 8. The oxygen-fuel combustor according to claim 1, wherein the center supply unit comprises: a first center supply unit configured to supply a primary fuel to the heating furnace and comprising a first center supply pipe through which the primary fuel to be supplied to the heating furnace is delivered; and a second center supply unit coupled to the center through-portion to supply a secondary fuel to the heating furnace and comprising a second center supply pipe through which the secondary fuel to be supplied to the heating furnace is delivered in a state in which the first center supply pipe is inserted into the second center supply pipe, and wherein the center nozzle unit comprises: a center nozzle coupled to the first center supply pipe and having a first injection hole formed therein, from which the primary fuel delivered from the first center supply pipe is injected; and a nozzle flange protruding from an outer peripheral surface of the center nozzle and coupled to the second center supply pipe, the nozzle flange having a second injection hole formed therein, from which the secondary fuel delivered from the second center supply pipe is injected.
 9. The oxygen-fuel combustor according to claim 8, wherein the second injection hole is obliquely formed in the nozzle flange so that an injection direction of the secondary fuel delivered from the second center supply pipe and an injection direction of the oxygen supplied from the oxygen supply unit cross each other.
 10. The oxygen-fuel combustor according to claim 1, wherein the oxygen through-portions include two to four oxygen through-portions spaced apart from each other in the circumferential direction.
 11. A method of injecting oxygen and a fuel, the method comprising: measuring an internal temperature of a heating furnace; comparing the internal temperature of the heating furnace, measured in the measuring, with a predetermined auto-ignition temperature; forming a first flame by injecting primary oxygen and secondary oxygen to the fuel when a result of the comparing is that the internal temperature of the heating furnace is less than the predetermined auto-ignition temperature; and forming a second flame by injecting only the secondary oxygen to the fuel when the result of the comparing is that the internal temperature of the heating furnace is equal to or greater than the predetermined auto-ignition temperature, wherein, in the forming the first flame, an injection amount of the primary oxygen is 30% or less of a total injection amount of oxygen, and an injection amount of the secondary oxygen is 70% or more of the total injection amount of oxygen.
 12. The method according to claim 11, wherein the forming the first flame comprises: injecting the fuel forward of a discharge head unit via a center nozzle unit provided at a center of the discharge head unit; injecting the primary oxygen forward of the discharge head unit via the center nozzle unit so as to form a fuel thickening region in which the primary oxygen and the fuel are injected in directions crossing each other and react with each other in front of the discharge head unit; and injecting the secondary oxygen forward of the discharge head unit via an oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from the center nozzle unit, so as to form an oxygen reaction region in which the secondary oxygen and the fuel are injected in directions crossing each other and react with each other in front of the discharge head unit, the oxygen reaction region being formed at a location farther from the discharge head unit than the fuel thickening region.
 13. The method according to claim 12, wherein the injecting the secondary oxygen comprises, at least one of: injecting the secondary oxygen forward of the discharge head unit via a first oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from the center nozzle unit, so as to form a first oxygen reaction region in which the secondary oxygen and the fuel are injected in directions crossing each other and react with each other in front of the discharge head unit, the first oxygen reaction region being formed at a location farther from the discharge head unit than the fuel thickening region; and injecting the secondary oxygen forward of the discharge head unit via a second oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from the center nozzle unit, so as to form a second oxygen reaction region in which the secondary oxygen and the fuel are injected in directions crossing each other and react with each other in front of the discharge head unit, the second oxygen reaction region being formed at a location farther from the discharge head unit than the fuel thickening region, wherein the first oxygen reaction region is formed in front of the discharge head unit at a location closer to the discharge head unit than the second oxygen reaction region, and wherein the first oxygen nozzle unit is closer to the center nozzle unit than the second oxygen nozzle unit.
 14. The method according to claim 12, wherein the forming the second flame comprises the injecting the fuel and the injecting the secondary oxygen, without the injecting the primary oxygen, compared to the forming the first flame.
 15. A method of injecting oxygen and a fuel, the method comprising: measuring an internal temperature of a heating furnace; comparing the internal temperature of the heating furnace, measured in the measuring, with a predetermined auto-ignition temperature; forming a first flame by injecting at least one of a primary fuel and a secondary fuel to the oxygen when a result of the comparing is that the internal temperature of the heating furnace is less than the predetermined auto-ignition temperature; and forming a second flame by injecting at least one of the primary fuel and the secondary fuel to the oxygen when the result of the comparing is that the internal temperature of the heating furnace is equal to or greater than the predetermined auto-ignition temperature, wherein, in at least one of the forming the first flame and the forming the second flame, at least one of an oxygen reaction region in which the primary fuel and the oxygen are injected in directions crossing each other and react with each other in front of a discharge head unit and two or more additional reaction regions in which the secondary fuel and the oxygen are injected in directions crossing each other and react with each other between the discharge head unit and the oxygen reaction region is formed.
 16. The method according to claim 15, wherein the forming the first flame comprises: injecting the oxygen forward of the discharge head unit via an oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from a center nozzle unit provided at a center of the discharge head unit, so as to form at least one of the oxygen reaction region in which the primary fuel and the oxygen are injected in directions crossing each other and react with each other in front of the discharge head unit and the additional reaction regions in which the secondary fuel and the oxygen are injected in directions crossing each other and react with each other, and at least one of: injecting the primary fuel to the oxygen reaction region via the center nozzle unit; and injecting the secondary fuel to the additional reaction regions via the center nozzle unit.
 17. The method according to claim 16, wherein the injecting the oxygen comprises: injecting the oxygen forward of the discharge head unit via a first oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from the center nozzle unit, so as to form a first oxygen reaction region in which the primary fuel and the oxygen are injected in directions crossing each other and react with each other in front of the discharge head unit; and injecting the oxygen forward of the discharge head unit via a second oxygen nozzle unit, provided in the discharge head unit so as to be spaced apart from the center nozzle unit, so as to form a second oxygen reaction region in which the primary fuel and the oxygen are injected in directions crossing each other and react with each other in front of the discharge head unit, wherein the first oxygen reaction region is formed in front of the discharge head unit at a location closer to the discharge head unit than the second oxygen reaction region, and wherein the first oxygen nozzle unit is closer to the center nozzle unit than the second oxygen nozzle unit.
 18. The method according to claim 16, wherein the forming the second flame comprises: injecting the primary fuel to the oxygen reaction region or injecting the secondary fuel to the additional reaction regions via the center nozzle unit; and injecting the oxygen to at least one of the oxygen reaction region or the additional reaction regions according to a type of the fuel injected in the injecting the primary fuel or the secondary fuel.
 19. The method according to claim 11, wherein, when the fuel and the oxygen are injected in at least one of the forming the first flame and the forming the second flame, an injection speed of the fuel injected forward of the discharge head unit from the center nozzle unit is equal to or less than 50% of an injection speed of the oxygen injected from the oxygen nozzle unit.
 20. The method according to claim 11, wherein, when the fuel and the oxygen are injected in at least one of the forming the first flame and the forming the second flame, an injection speed of the oxygen injected from the oxygen nozzle unit ranges from 100 m/s to 400 m/s. 